In many applications where a power source is utilized to drive a mechanical apparatus it is necessary to couple the power source through a variable ratio drive mechanism to the driven apparatus. A transmission is most predominantly used in this manner for the transfer of power from the motor of an automobile to the wheels. The features most commonly sought in a transmission of this type are numerous drive ratios to achieve the maximum efficiency from the power source, substantial power handling capability, reliability, low cost and simplicity in design and manufacture.
The most common transmission in use for vehicular applications utilizes a plurality of shaft mounted gears. The gears and shafts are transferred from one configuration to another by means of a control linkage to vary the drive ratio. A transmission of this type requires the manufacture of a large number of differing but precisely machined parts.
Another general type of transmission has been developed in which a tapered roller is driven by discs with the disc or rollers relatively movable to produce contact at different points along the roller and therefore produce varying drive ratios between the rollers and discs. Such a configuration is often used when it is desirable to have a continuously varying drive ratio in which case a smooth roller is utilized. A transmission of this type is shown in U.S. Pat. No. Re. 26,917 to Bickenbrock.
There exists a need for an improved mechanical transmission having a large number of drive ratios, easily manufactured parts, and capable of handling a wide range of power levels.